This application claims priority to Patent Cooperation Treaty (PCT) application number PCT/IB98/01685, filed Oct. 2, 1998, which in turn claims priority to German patent application number 197 43 807.5, filed Oct. 2, 1997.
The invention pertains curved elements for forming the skating surface of a skating ring. The invention includes a single- or double-curved pre-shaped shell segment made of wood whereby the shell segment forms the skating surface of a skating ring.
Skating rings, in particular those used by inline skaters, bicycle riders or similar, exist in numerous indoor and outdoor variations. The skating rings are comprised of many individual elements that are placed adjacent to each other, whereby the elements display straight, sloping, arched or curved or cylindrical respectively, spherical or similar skating surfaces. The skating surfaces can be made of wood, steel, plastic or concrete.
The curved elements found in the skating rings, for example in so called bowls, are manufactured in such a manner that flat shell segments made of wood or steel are fitted onto a base scaffold made of wood or steel whose contour approximately forms a bowl. Here the shell segments which were first cut to size are fastened on one side to the base scaffold in order to be able to attach the remaining surface by the use of bending force. Due to this undefined pressing down of the shell segments it is not always possible to achieve a smooth transition to the next shell segment.
In addition it is impossible to bend such large and highly stressed shell segments in two directions so that steps arise at the seams to the adjacent shell segments which inevitably lead to falls and therefore can lead to significant injuries.
A single curved shell segment of the art mentioned for curved elements for skating rings is known from DE U 90 10 527 whereby this shell segment is made of several plane-like wood layers which are glued together. By placing abutting shell segments onto a base scaffold a skating surface (for skaters) is formed. The disadvantage of this known shell segment is that these non-pre-shaped shell segments can only be attached to the base scaffold by the use of bending force. This leads to difficulties during construction and to steps and cracks between the abutting shell segments.
It is furthermore not possible to realize a uniform spherical skating surface for so-called bowls as there is no simple solution for the manufacture of pre-shaped double curved shell segments.
Such shell segments, i.e. shell segments that have adopted their final and lasting double-curved form due to a prefabrication, cannot be manufactured using conventional processes and plants. Such conventional processes are as a rule conceived for the manufacture of pre-formed parts for furniture in large numbers, whereby the pre-formed parts are developed as double-curved shell segments. The starting material is as a rule glued multiply plywood sheet which already exhibits the final thickness of the pre-formed part. As such pre-formed parts are significantly thinner and smaller than the double-curved shell segments for curved elements for skating rings the known plants are not capable of raising the necessary force in order to manufacture the shell segments according to the invention from conventional multiply plywood sheets. Indeed an appropriate enlargement of such plants is conceivable in order to manufacture the shell segments according to the invention using conventional processes, it is however to be expected that during the bending of thick shell segments cracks in the surface would result, especially in those places with increased tensile stress.
In addition such plants would be due to their size and complexity so cost intensive that the manufacturing costs of the shell segments would not be economically justifiable.
For this reason the objective of the invention is
to create a shell segment for curved elements for complex skating rings whose manufacturing and fabrication expense is minor, as well as
to indicate a process for the manufacture of pre-shaped single- and double-curved shell segments made of wood.
The objective described above is achieved by pre-shaping the shell segments before the construction begins so that they can subsequently be fixed free of stress and precisely onto the skating ring scaffold.
The objective is also met in that a process for the manufacture of such shell segments is recommended which is characterized by the following process steps:
a. each individual layer of wood is bent into it""s final shape;
b. the bent individual layers of wood are stacked to manufacture a shell segment;
c. the individual stacked layers of wood are joined without the application of stress.
The main advantage of the invention is that in particular the so-called bowls can be cost effectively and simply manufactured or constructed respectively. This applies also for the curved elements which are individually laid out for the requirements as well as those for the existing skating rings.
This results in a skating surface that is free of steps and partial holes.
In addition it proves to be of advantage that due to the almost stress-free fitting of the shell segments onto the scaffold, which preferably is comprised of vertical support elements and horizontally running ribs, very few cracks occur in the skating surface.
It is of advantage that the shell segments are comprised of individual layers of wood which are laid on top of each other and joined to each other. Each layer of wood is preferably bent on a clamping device and then laid without the application of stress on to a further layer of wood and joined to it.
Preferably the shell segments are made of wood so that the individual layers of wood can be glued to each other.
Due to the CIM technology (computer aided machining of the support columns, the ribs and computer aided bending of the shell segments) applied here it is also possible to precisely manufacture the vertical support elements and the horizontally arranged ribs which join the support elements to each other.
The support elements and the ribs are developed in such a way that they contact the underside of the shell segments at least along a line of contact, preferably along a surface of contact. The bearing surface elements which are placed on the sides of the support elements assist the surface contact of the shell segments.